In a conventional binding of this type, for example that disclosed in German Offenlegungsschrift No. 24 32 711 (corresponds to U.S. Pat. No. 3,933,363), the spring housing is constructed in the form of a U-shaped support part, its end being supported swingably in the bearing block and its side parts having slotted holes which form a guideway for a locking member. The locking spring is supported on the locking member which in the downhill skiing position engages a control cam of the control part but in the released position is disposed in a recess in the control part. The support part is swivelled by means of the release lever, which is supported rotatably on the support part and is supported on the locking part.
This binding has the disadvantage that, during a voluntary release, the locking spring must be compressed by means of the release lever in order to swing the support part sufficiently upwardly so that the locking member leaves the control cam and comes to rest in the recess in the locking part. Therefore, the energy required to effect the voluntary release of the binding is considerable. Furthermore, the binding is susceptible to breakdowns, due to the various guide slots and due to the spring, which is not protected on all sides.
A similar binding is illustrated in German Offenlegungsschrift No. 29 00 239. Here too the locking spring is stored in a U-shaped support part, in the two sides of which are provided slotted holes which form a guideway for a locking member which is biased by a locking spring. The locking part is supported pivotally on an axle which rests with its two ends in semicircular notches provided in the upper boundary surfaces of the side parts of the bearing block. Such ends are gripped under by locking steps of the release lever in the locked position of the binding. The release lever is supported swingably on the binding housing.
If a voluntary release is to be started in this binding, the release lever is pressed down against the action of the spring. The locking steps of the lever thereby disengage from the axle of the locking part and the binding housing is swung upwardly by means of arcuate slotted holes, into which engages the axle of the locking part.
The force for the voluntary release of this binding is substantially reduced as compared with the first-mentioned binding. Furthermore, this force is constant and therfore independent from the preset initial tension of the locking spring. However, this binding has the disadvantage that the two locking steps of the release lever lie outside the binding housing and are therefore constantly exposed to dirt. Furthermore, this binding is of relatively complicated construction, due to the various guide slots and the fact that the support part which serves as a spring housing is not closed all around.
While in the above-discussed conventional safety ski bindings the support part which forms the spring housing and the binding housing are supported for rotation on a common axle, in the case of the binding according to German Offenlegungsschrift No. 26 28 748 the swivel axes for the swivelling part which carries the sole holder and the stepping spur and for the spring housing are spaced from one another, one being provided at the rear lower end of the bearing block and the other in the area of its upper side. The spring housing is here designed as a cylinder in which one spring abutment is formed by a setscrew which effects the adjustment of the initial tension of the spring and the other spring abutment is formed by a piston having a piston rod. This piston is not guided on the inner wall of the cylinder, but has sufficient clearance with respect to same so that not only a linear movement of the piston rod is possible, but also a certain degree of swivelling of the same.
In this binding, during a voluntary release, the end of the cylindrical spring abutment which is remote from the piston is lifted by means of a hand lever from a stop surface which is followed by an inclined ramp. Thus, the force which must be manually produced is not constant, as is often desired, but depends on the initial tension of the locking spring. Moreover, recreating the locked condition of the binding requires much strength, since the end of the cylinder which is remote from the piston must be pressed manually over the inclined ramp and onto the stop surface, whereby the full force of the locking spring be overcome.
A goal of the invention is to overcome the enumerated disadvantages of the conventional bindings and to provide a binding of the above-disclosed type which can be voluntarily released without a large amount of force and can thereafter be moved back into the downhill skiing position, which is relatively simple in its design, and in which the most important elements are protected against outside influences like dirt and damage.